Lots of good info in the above posts. The only thing I would add here is that if your track means a lot to you, then you might not want to sign it over. The more that music means to you personally, then the more you should consider retaining your rights to that track...

For a wild hair example, if I were PVD trying to get For An Angel signed, I would be much more stringent on the degree of rights transfer than if I was signing over, Nothing but you

Make sure you have a clear understanding of how long your transfer of rights will be... if you ever see, "In Perpetuity"... RUN!!! otherwise known as, for life